Bushmaster with a jammed bolt carrier assembly

[U.S.SFC_RET]

Yep this a first I have seen. I was in a gun shop down in Georgia when two young men walked in with a brand new Bushmaster. One of them tells the Owner that he was firing his Bushmaster when it stopped firing.
The bolt carrier assembly jammed backward into the buffer/ stock assembly. If it weren't for the forward assist The gun never would have come apart.
The bolt assembly is still extremely tight and the lugs are locked into the chamber. The bolt carrier assembly moved with extreme resistance forward.
Did this young buck neglect something during assembly?
I have never seen a bolt carrier assembly jam like this in my 20 years in the Army with the Colt M16 family. This is a Bushmaster. I am very curious.

 

[Redhat]

How did the fwd assist help get the gun apart? Was the carrier competely in the stock? I have seen folks forget to install the firing pin retaining pin and cause it to lock up. He may have installed the fp retining pin in the wrong side of the carrier, that causes friction against the inside of the rteceiver. Also seen the bent / broken buffer retainer cause problems.

Let us know what the found out.

 

[U.S.SFC_RET]

The forward assist ratcheted forward with each tooth on the bolt carrier. Slowly the bolt went forward. I went back to Maryland. I suspected the firing pin retaining pin but whan I seen the firing pin was in place as the bolt carrier moved forward I dismissed it. He, the young "adult stated he shot about a half dozen times with no problems until the bolt carrier siezed in the stock about 4/5ths of the way in.
Honestly I don't believe the bolt rotated fully for some reason on the return stroke and froze into place. Could this be a mispositioned bolt during an assembly?

 

[rcmodel]

No.

It will only fit on the carrier one way and still work at all. The cam pin won't go through the bolt body from the wrong side if the bolt is made properly.

I'd almost suspect the buffer tube retainer plunger & spring came out due to a loose or improperly installed buffer tube. If the little spring got crunched up between the upper receiver and bolt carrier it would do exactly as you indicated. Or if the pin & spring fell into the trigger group, it could cause the hammer to fail to cock and rub hard on the bolt carrier.

rc

 

[BADUNAME27]

A number of possible scenarios.

1. Foreign material
2. galled surfaces
3. Broken forward assist (personally seen this a few times here in Iraq)
4. Firing pin installed behind the retaining pin and it fell out and caused an obstruction
5. buffer retaining pin/spring assy came out of the pin bore and caused an obstruction
6. Brass shell casing jammed up in the raceway that the bolt cam pin tracks in (seen this several times in iraq as well)
7. Bent gas key (very rare)